Coronary heart disease (CHD) continues to be the leading cause of death in African American women. They have a high prevalence of CHD risk factors such as obesity, hypertension, and diabetes mellitus. Typically, African American women have sedentary lifestyles; thus they can achieve the greatest heath benefits from regular, moderate-intensity, physical activity. Most exercise training and other therapeutic interventions have not targeted these women, and few studies have been culturally-specific, sustainable, or efficacious in altering CHD risk factors. This study is a randomized trial using churches in the Baltimore area and will compare a self-help behavioral intervention that encourages the same level of physical activity. Participants are sedentary African American women who are over the age of 25 years. The specific aim of the intervention is to increase total daily energy expenditure by 150 kilocalories per day and time spent in moderate-intensity physical activity by 30 minutes per day. We assess effects of increased physical activity on selected cardiovascular risk factors, e.g., peak oxygen uptake, blood pressure, HDL cholesterol, serum insulin, and plasma glucose. Multiple churches are randomized into intensive or minimal intervention status, and women from the church will be recruited for a total of 100 women in each group. The intensive behavioral intervention consists of once-per-week aerobic classes conducted in the church with weekly handouts and monthly newsletters on topics related to information and support for aerobic exercise. Volunteer lay leaders are trained to become exercise instructors to supplement the certified instructors in conducting the intervention. The proposed intervention fills an existing gap. It examines a culturally-sensitive physical activity intervention conducted in a community setting and its association with increases daily energy expenditure in African American women - a group of high health risk women who are sedentary for whom regular physical activity can provide benefits.